1. Field of the Invention
The present invention relates to a structure for housing in a housing box an electrical junction box mainly installed in a vehicle.
2. Description of the Related Art
As disclosed in Japanese Patent Application Laid-Open Publication No. 2001-061216, in the case where an electrical junction box is housed and fixed in a housing box, generally, first engagement parts are provided in an outer peripheral portion of the electrical junction box and second engagement parts engaged with the first engagement parts are also provided in an inner peripheral portion of the housing box.
FIG. 1 is a perspective view showing a relationship between a related electrical junction box and a housing box. FIG. 2 is a cross-sectional view showing a state where the electrical junction box is housed in the housing box when viewed from the front. FIG. 3 is an enlarged view of a section III in FIG. 2.
Reference numeral 110 denotes an electrical junction box and reference numeral 130 denotes a housing box for housing the electrical junction box 110. On the outside of the housing box 130, a fixing bracket 170 is attached for fixing the housing box 130 to a vehicle body with a bolt. The electrical junction box 110 has electric components (not shown) housed in a space formed by attaching upper and lower cases 111 and 112 to each other, which are made of resin. The housing box 130 consists of a lower cover 131 and an upper cover 132 engaged therewith so as to cover a front side of the lower cover.
The upper case 111 of the electrical junction box 110 has a rectangular box shape having a rectangular front wall 111A, upper and lower walls 111B and left and right side walls 111C. Specifically, the upper and lower walls 111B and the left and right side walls 111C are contiguously provided on four sides of the front wall 111A. On outer surfaces (external side surfaces 111Ca) of the left and right side walls 111C of the upper case 111, elastic engagement arms 117 having engagement projections 117a attached thereon and guide rails 116 and 118 which serve as a guide when the electrical junction box 110 is inserted into the housing box 130 are provided so as to project from the outer surfaces.
The guide rails 116 and 118 are disposed on both sides of the elastic engagement arms 117 so as to protect the elastic engagement arms 117. In this case, the guide rails 118 on one side are formed so as to be divided into upper and lower parts in consideration of die-releasing (a die-releasing direction is indicated by the arrow K) of an injection molding die in formation of the elastic engagement arms 117.
The lower cover 131 of the housing box 130 consists of a backside wall 131A, a lower wall 131B, left and right side walls 131C, a lower front wall 131D and left and right front walls 131E, all of which surround a space 133 for housing the electrical junction box 110. The lower cover 131 has an opening from its front center portion to its upper surface, which is not covered with the lower front wall 131D and the left and right front walls 131E. In inner surfaces (internal side surfaces 131Ca) of the left and right side walls 131C, steps (engagement parts) 137 are provided, which are engaged with the elastic engagement arms 117 of the electrical junction box 110.
When the electrical junction box 110 is housed in the housing box 130 having the configuration described above, the electrical junction box 110 is inserted into the lower cover 131 from above. Accordingly, the guide rails 116 and 118 are guided by the internal side surfaces of the lower cover 131 and thus the electrical junction box 110 is smoothly inserted into the space 133 in the lower cover 131. When the electrical junction box 110 is inserted, interference between the engagement projections 117a of the elastic engagement arms 117 and the internal side surfaces 131Ca of the lower cover 131 causes elastic deformation of the elastic engagement arms 117. Moreover, the engagement projections 117a of the elastic engagement arms 117 elastically restored by further inserting the electrical junction box 110 are engaged with the steps 137 in the internal side surfaces 131Ca of the lower cover 131. Thus, the electrical junction box 110 is locked to the lower cover 131. In this state, the upper cover 132 is placed on the lower cover 131 and locked thereto. Thus, the electrical junction box 110 can be protected in a state of being housed and fixed in the housing box 130.
In the related structure described above, the elastic engagement arms 117 are provided so as to project from the external side surfaces 111Ca of the electrical junction box 110. Thus, the elastic engagement arms 117 can be deformed or damaged when dropped or hit, particularly, during a low-temperature operation in winter. When the elastic engagement arms 117 are deformed or damaged, there is a problem that the electrical junction box 110 cannot be normally fitted into the housing box 130 or rattling occurs even if the electrical junction box 110 is fitted.
Moreover, in the case of the related structure described above, the guide rails 116 and 118 are expected to prevent deformation or damage of the elastic engagement arms 117. However, extra space is required for the projections. Thus, there arises a drawback to a demand for space-saving.
These points are equally true in the case where engagement convex parts, instead of the elastic engagement arms, are provided so as to project from the external side surfaces 111Ca of the electrical junction box 110.
Moreover, since the guide rails 118 on one side are formed in a divided pattern in consideration of die-releasing in injection molding, there may arise a problem in guiding.